You might recall my very own hyperbolic concept of Web Pi -- where Pi represents the ratio of a circle's circumference to its diameter, which (being transcendental) is a number which you can never quite reach!
In a well-balanced article, Web 2.0 and New Approaches to Software, Peter Varhols comments:
"Web 2.0 is about more than the technology and coding. ... You have to integrate technology with community and business innovations in order to have a valid Web 2.0 application concept. Without the community and business innovation, you might have a useful application, but you almost certainly lack an application that dramatically changes your business. ... That is the key to Web 2.0. Not the technology, which is by itself not particularly innovative. The innovation is how that technology is applied to problems in business and society. In other words, it is not enough to write a Web application that uses Ajax, REST design, and scripting languages; it is about using these technologies in pursuit of innovation."
By my reckoning, Peter's article nicely positions Web 2.0 and then finishes off with:
"To paraphrase former Supreme Court Justice Potter Stewart, who wrote that he couldn't describe pornography but knew it when he saw it, it may not be possible to fully describe Web 2.0, but you will know it when you see it."